Chennai Petroleum Corporation Technician Interview Questions and Answers

RS 485 is a multi-point communication standard while RS 232 is a point-to-point communication standard.

• RS 485 supports up to 32 devices on a single bus while RS 232 only supports two devices.

• RS 485 uses differential signaling for noise immunity while RS 232 uses single-ended signaling.

• RS 485 can transmit data over longer distances than RS 232.

• RS 485 is commonly used in industrial automation and control systems while RS

Protocol is a set of rules and guidelines that govern the communication between devices or systems.

• Protocols ensure that devices or systems can communicate with each other effectively and efficiently.

• They define the format, timing, sequencing, and error checking of messages exchanged between devices or systems.

• Examples of protocols include TCP/IP, HTTP, FTP, and SMTP.

• Protocols can be implemented in hardware, software, ...read more

PLC stands for Programmable Logic Controller. It is a digital computer used for automation of electromechanical processes.

• PLC is used in industrial automation to control machinery and processes.

• It is programmed using ladder logic or other programming languages.

• PLC can be used in various applications such as manufacturing, transportation, and energy.

• Examples of PLC brands include Siemens, Allen-Bradley, and Mitsubishi.

• P...read more

There are several types of PLCs, including modular, compact, rack-mounted, and software-based PLCs.

• Modular PLCs are designed to be expandable and customizable.

• Compact PLCs are smaller and more cost-effective than modular PLCs.

• Rack-mounted PLCs are designed to be mounted in a standard equipment rack.

• Software-based PLCs run on a computer and use specialized software to emulate a physical PLC.

• Other types of PLCs include s...read more

Safety is the state of being free from harm or danger.

• Safety involves identifying and assessing potential hazards

• It requires taking measures to prevent accidents and injuries

• It involves following established safety protocols and procedures

• Safety also includes being prepared for emergencies and knowing how to respond

• Regular training and education on safety practices is crucial

The chiller refrigeration cycle is a process that removes heat from a space or substance using a refrigerant.

• The cycle starts with the compressor compressing the refrigerant gas.

• The compressed gas then flows through the condenser where it releases heat and becomes a liquid.

• The liquid refrigerant then flows through the expansion valve, where it expands and becomes a gas again, absorbing heat in the process.

• The gas then ...read more